There are two main objectives of the Bioinformatics and Biostatistics Core (BSIC): 1) provide leadership on the application of statistical/informatics reasoning and methods in Center research, including the design of experimental and observational studies and analysis or the resulting data; 2) develop and apply innovative statistical methods to Center research data and to thereby improve scientific inferences drawn by Center investigators. Collaboration -the biostatistics and bioinformatics experts in the BSIC will actively participate with members of the Center on specific research programs. For example, Drs. Zeger and Dominici currently collaborate with Drs. Samet on the NMMAPS project and Dr. Irizarry collaborates with Dr. Tankersley on a toxicology study. New collaborations will arise as they are needed through informal discussions among faculty or by a formal request to the director. BSIC faculty are experts in the design of both observational and experimental studies. They work with their colleague to: precisely define the hypotheses so that they are maximally testable; choose the study design; define the exposure and health outcome measures as precisely as possible, plan data management and analytic methods. Where existing methods are inadequate, they will also develop novel methods to fill the void.